The present invention relates to a process and apparatus employing electroerosion. The journal "Technische Rundschau", No. 29, 1985, Hallwag-Verlag, Berne, Switzerland, pg. 11 discloses a process for electroeroding an electrode fixed in a spindle sleeve of a countersunk erosion machine in order to calibrate the length and/or diameter of the electrode. The machine also has a machine table carrying a counter electrode. The calibrated electrode is used for countersinking of workpieces, which are also mounted on the machine table. The machine also employs a tool electrode changer and/or a work pallet system with a complete mounting or clamping system. The disclosure also states that it is difficult to align a workpiece on the table and that it can be advantageous to measure the precise position of the workpiece using mechanical or electronic probes, which are, for example, measurement electrodes in the tool changer.
Electrode changers for countersunk erosion machines were exhibited at the EMO Machine Tool Exhibition in Hanover in 1981 by the Swedish firm 3R. This exhibit also demonstrated that complicated countersinking or countersunk electrodes can be subdivided into several partial electrodes.
The electrode subdivision according to the aforementioned 3R system, in principle makes very severe demands on the electrode manufacture and is therefore only used in special cases. JP-OS No. 53-24200/74 describes a wire cutting machine, which uses the fragments produced during cutting erosion for a conical widening by planetary erosion, said fragments serving as the countersunk electrode. This concept is limited to producing a countersunk electrode adapted to the exact shape of the previously cut opening in the workpiece. This machine cannot be used for the general production of more complicated countersunk electrodes. It is known to work countersunk electrodes on another eroding machine, where they act as workpieces and following the production and following the production thereof as an "electrode", they are used as a countersunk electrode on another machine. Inter alia this suffers from the disadvantage that the production sequence (from the crude electrode to the completely worked workpiece) cannot be automated. Thus, these are purely auxiliary processes, which are rarely used.
It is also known in the art that wire cutting means can be fitted to a spindle sleeve of a countersinking erosion machine. An example for this is provided in the journal "EDM-Digest", January/February 1985, pg. 13 in an advertisement by EDM Technology, New York, USA.